(A) One YN600EX-RT II can be used as master unit to trigger another YONGNUO YN600EX-RT or Canon's 600EX-RT, and live display the flash groupings of slave unit and recycling information. Supports Wireless Optical Slave function --- The YN600EX-RT supports YONGNUO, Canon's and Nikon's wireless optical master signal, supports S1 and S2 pre flash cancel mode.
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